Not Applicable.
Polyamide gelling agents for use in transparent gel formulations such as transparent candles and personal care products such as clear deodorant gels have caused products into which they are added to exhibit blooming and syneresis. Known clear candle compositions utilizing commercially available polyamide resins such as VERSAMID(copyright) 940 or VERSAMID(copyright) 1655 as a gelling resin demonstrated poor long-term resistance to blooming and syneresis. Similar problems have occurred with clear gel personal products containing polyamide gelling agents and are described in U.S. Pat. No. 5,500,209, the Background of the Invention section of which is incorporated herein by reference.
The present invention pertains to a method for reducing or eliminating blooming and/or syneresis in a gel formulation comprising adding to an organic mixture an effective amount of a polyamide gelling agent having a softening point of less than about 105xc2x0 C. wherein the polyamide is the reaction product of one or more diamines, optionally one or more mono-amines, one or more hydrogenated C36 dimer acids, optionally one or more C2-22 dicarboxylic acids, and optionally one or more C2-22 monocarboxylic acids.
None
The term xe2x80x9cgelxe2x80x9d as used herein is defined in Almdale et al. (Polymer Gels and Networks, Vol. 1, No. 5 (1993)) according to the following two criteria: (1) a substance that consists of two or more components, one of which is a liquid, present in substantial quantities; and (2) a gel is a soft material which is solid or solid-like. A gel can also be defined according to its rheological properties. Thus, the term xe2x80x9cgelxe2x80x9d applies to systems having a value Gxe2x80x2(w) that is higher than its value of Gxe2x80x3(w) at low frequencies. Gxe2x80x2(w) is the storage modulus which exhibits a pronounced plateau at higher frequencies (on the order of 1-100 radians/second), and Gxe2x80x3(w) is the loss modulus which is considerably smaller than the storage modulus in the plateau region. A gel is free-standing or self-supporting in that its yield value is greater than the sheer stress imposed by gravity.
The diamines that can be used to make the polyamides according to the invention are comprised of two or more aliphatic or cycloaliphatic, linear or branched, saturated or unsaturated diamines which when copolymerized with the acid moieties described herein will produce a polyamide resin having a softening point of less than about 105xc2x0 C. Examples of the diamines that can be present in the diamine mixture include, but are not limited to, ethylene diamine, 1,2- and 1,3-propylene diamine, teramethylene diamine, hexamethylene diamine, octamethylene diamine, 1,2-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane and combinations thereof. The diamines also include polyether diamines which can be poly(ethylene oxide) xcex1,xcfx89-diamine or poly(propylene oxide) xcex1,xcfx89-diamine or poly(ethylene-co-propylene oxide) xcex1,xcfx89-diamine of various molecular weights and as well poly(ethylene oxide) or poly(propylene oxide) monoamines and triamines. Polyether amines are commercially available as, for example, JEFFAMINE(copyright)(trademark) polyether diamines, available from Huntsman Chemical.
The monoamines that can be used to make the polyamides according to the invention include any aliphatic or alicyclic, saturated or unsaturated, linear or branched chain monoamine having from C2 to C60 carbon atoms. Polyether monoamines are also included and are commercially available as, for example, JEFFAMINE(copyright)(trademark) polyether monoamines, available from Huntsman Chemical.
The hydrogenated dimer acids are those made by polymerizing unsaturated mono- and polyunsaturated fatty acids or a mixture thereof. Such acids can be made by the processes described in U.S. Pat. Nos. 2,955,121; 3,412,039; and 3,507,890, the entire contents of each of which is incorporated herein by reference. Such dimer acids are commercially available as, for example, EMPOL(copyright) 1008, EMPOL(copyright) 1004, EMPOL(copyright) 1025, EMPOL(copyright) 1011, or EMPOL(copyright) 1062 dimer acid from Cognis Corporation, Cincinnati, Ohio.
The C2-22 dicarboxylic acids can be one or a mixture of dicarboxylic acids having from 2 to 22 carbon atoms examples of which include, but are not limited to malonic acid, succinic acid, adipic acid, azelaic acid, dodecanedioc acid and octadecenedioc acid.
The C2-22 monocarboxylic acids can be any aliphatic, saturated or unsaturated, linear or branched monocarboxylic acid having from 2 to 22 carbon atoms. Examples of such acids include, but are not limited to, capryic acid, lauric acid, palmitic acid, palmitoleic acid, oleic acid, linoleic acid, isostearic acid, arachidic acid and arachidonic acid.
A preferred polyamide resin is the reaction product of a hydrogenated dimer acid, stearic acid, azelaic acid, ethylene diamine, and a polypropyleneoxide diamine having a mole. Wt. of about 230. Another preferred polyamide resin is the reaction product of a hydrogenated dimer acid, stearic acid, azelaic acid, ethylene diamine, and hexamethylene diamine.
Candle formulations containing polyamide resin gelling agents according to the invention exhibit better color stability in the melt and better compatibility with other ingredients than standard candle formulations. These lower softening point resins allow for formulated gels that can melt and wick at lower temperatures resulting in less thermal degradation and less discoloration of the melt. Also, higher softening point resin result in formulated gels with higher melting points which can approach the flash point of the fragrance or other gel ingredients and cause flaring of the whole candle surface. While the softening point of the polyamide resins according to the invention are less than about 105xc2x0 C., they are preferably between 65xc2x0 C. to 95xc2x0 C., even more preferable between 75xc2x0 C. to 90xc2x0 C. have unexpectedly been found to provide better compatibility and less syneresis and blooming.
The polyamide resins according to the invention can also be used in such products as air-freshener gels where the polyamide is used to gel a fragrance composition, but not for burning. Polyamides are known to have desirable fragrance release and can be used in air-fresheners where the material, unlike candles, do not require heat to release the fragrance. Such gels are known to release their desired fragrance more readily. Other uses of the polyamide resins according to the invention include gelling agents for personal care and cosmetics applications such as deodorant gels and lipstick respectively.
The polyamide resins according to the invention can also be used in personal care products, e.g., cosmetics such as eye make-up, lipstick, foundation make-up, costume make-up, as well as baby oil, make-up removers, bath oil, skin moisturizers, sun care products, lip balm, waterless hand cleaner, medicated ointments, ethnic hair care products, perfume, cologne, and suppositories. Formulations to prepare such materials are well known in the art. For example, U.S. Pat. Nos. 3,615,289 and 3,645,705 describe the formulation of candles. U.S. Pat. Nos. 3,148,125 and 5,538,718 describe the formulation of lipstick and other cosmetic sticks. U.S. Pat. Nos. 4,275,054, 4,937,069, 5,069,897, 5,102,656 and 5,500,209 each describe the formulation of deodorant and/or antiperspirant. Each of these U.S. Patents is hereby incorporated fully herein by reference.
The method according to the invention comprises the addition of a polyamide resin gelling agent to an organic mixture. The resulting mixture is a gel. The organic mixture is any combination of organic compounds that when mixed with a gelling agent form a gel. Such compounds include, for example, fatty alcohols and fatty acid esters including naturally occurring oils such as castor oil, peanut oil, safflower oil, sunflower oil, corn oil or cod liver oil and synthetic esters of mono and difunctional alcohols and fatty acids.
The amount of polyamide resin gelling agent that can be used in the process according to the invention is an effective amount which is any amount that will eliminate or reduce the amount of blooming and/or syneresis in the gel formed as a result of mixing the polyamide gelling agent and the organic resin. The effective amount will be readily ascertainable by one of ordinary skill in the art. Typically, the amount will be in the range of from about 10% by weight of the formulation to about 90% by weight of the formulation and preferably from about 25% by weight of the formulation to about 60% by weight of the formulation.